Aldosterone Stimulates K Secretion across Mammalian Colon Independent of Na Absorption

Authors

Gerhard Rechkemmer
Dan R. Halm, Wright State University - Main CampusFollow

Document Type

Article

Publication Date

1-1989

Abstract

K transport across guinea pig (Cavia porcellus) distal colon was measured in vitro using isotopically determined unidirectional fluxes. Aldosterone stimulated electrogenic Na absorption, as measured by amiloride-sensitive short-circuit current (I_sc), and reduced net K absorption from +2.5 ± 0.2 µEq/cm² per hr to +0.8 ± 0.3 µEq/cm² per hr (mean ± SEM). Amiloride addition to the mucosal solution did not enhance net K absorption, as expected if inhibiting active Na absorption would reduce active K secretion as in the distal nephron. The amiloride-insensitive I_sc was -1.0 ± 0.2 µEq/cm² per hr (mean ± SEM) and was inhibited by mucosal addition of Ba, a K channel blocker. Addition of bumetanide to the serosal solution also inhibited this negative I_sc, and K transport returned to the control level of net absorption. Thus, the amiloride-insensitive, negative I_sc is consistent with active K secretion stimulated by aldosterone. This stimulation of an active K secretory pathway by aldosterone occurred without altering the active K absorption pathway that also is present. These results indicate that the aldosterone-stimulated K secretory pathway operates independently of the amiloride-sensitive Na absorption pathway, which also is stimulated by aldosterone.

Repository Citation

Rechkemmer, G., & Halm, D. R. (1989). Aldosterone Stimulates K Secretion across Mammalian Colon Independent of Na Absorption. Proceedings of the National Academy of Sciences of the United States of America, 86 (1), 397-401.
https://corescholar.libraries.wright.edu/ncbp/992